{ "schema_version": "1.6.1", "id": "RPI-CVE-2024-26882", "modified": "2026-10-09T11:39:44Z", "upstream": [ "CVE-2024-26882" ], "published": "2024-04-17T10:29:01Z", "summary": "net: ip_tunnel: make sure to pull inner header in ip_tunnel_rcv()", "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ip_tunnel: make sure to pull inner header in ip_tunnel_rcv()\n\nApply the same fix than ones found in :\n\n8d975c15c0cd (\"ip6_tunnel: make sure to pull inner header in __ip6_tnl_rcv()\")\n1ca1ba465e55 (\"geneve: make sure to pull inner header in geneve_rx()\")\n\nWe have to save skb->network_header in a temporary variable\nin order to be able to recompute the network_header pointer\nafter a pskb_inet_may_pull() call.\n\npskb_inet_may_pull() makes sure the needed headers are in skb->head.\n\nsyzbot reported:\nBUG: KMSAN: uninit-value in __INET_ECN_decapsulate include/net/inet_ecn.h:253 [inline]\n BUG: KMSAN: uninit-value in INET_ECN_decapsulate include/net/inet_ecn.h:275 [inline]\n BUG: KMSAN: uninit-value in IP_ECN_decapsulate include/net/inet_ecn.h:302 [inline]\n BUG: KMSAN: uninit-value in ip_tunnel_rcv+0xed9/0x2ed0 net/ipv4/ip_tunnel.c:409\n __INET_ECN_decapsulate include/net/inet_ecn.h:253 [inline]\n INET_ECN_decapsulate include/net/inet_ecn.h:275 [inline]\n IP_ECN_decapsulate include/net/inet_ecn.h:302 [inline]\n ip_tunnel_rcv+0xed9/0x2ed0 net/ipv4/ip_tunnel.c:409\n __ipgre_rcv+0x9bc/0xbc0 net/ipv4/ip_gre.c:389\n ipgre_rcv net/ipv4/ip_gre.c:411 [inline]\n gre_rcv+0x423/0x19f0 net/ipv4/ip_gre.c:447\n gre_rcv+0x2a4/0x390 net/ipv4/gre_demux.c:163\n ip_protocol_deliver_rcu+0x264/0x1300 net/ipv4/ip_input.c:205\n ip_local_deliver_finish+0x2b8/0x440 net/ipv4/ip_input.c:233\n NF_HOOK include/linux/netfilter.h:314 [inline]\n ip_local_deliver+0x21f/0x490 net/ipv4/ip_input.c:254\n dst_input include/net/dst.h:461 [inline]\n ip_rcv_finish net/ipv4/ip_input.c:449 [inline]\n NF_HOOK include/linux/netfilter.h:314 [inline]\n ip_rcv+0x46f/0x760 net/ipv4/ip_input.c:569\n __netif_receive_skb_one_core net/core/dev.c:5534 [inline]\n __netif_receive_skb+0x1a6/0x5a0 net/core/dev.c:5648\n netif_receive_skb_internal net/core/dev.c:5734 [inline]\n netif_receive_skb+0x58/0x660 net/core/dev.c:5793\n tun_rx_batched+0x3ee/0x980 drivers/net/tun.c:1556\n tun_get_user+0x53b9/0x66e0 drivers/net/tun.c:2009\n tun_chr_write_iter+0x3af/0x5d0 drivers/net/tun.c:2055\n call_write_iter include/linux/fs.h:2087 [inline]\n new_sync_write fs/read_write.c:497 [inline]\n vfs_write+0xb6b/0x1520 fs/read_write.c:590\n ksys_write+0x20f/0x4c0 fs/read_write.c:643\n __do_sys_write fs/read_write.c:655 [inline]\n __se_sys_write fs/read_write.c:652 [inline]\n __x64_sys_write+0x93/0xd0 fs/read_write.c:652\n do_syscall_x64 arch/x86/entry/common.c:52 [inline]\n do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83\n entry_SYSCALL_64_after_hwframe+0x63/0x6b\n\nUninit was created at:\n __alloc_pages+0x9a6/0xe00 mm/page_alloc.c:4590\n alloc_pages_mpol+0x62b/0x9d0 mm/mempolicy.c:2133\n alloc_pages+0x1be/0x1e0 mm/mempolicy.c:2204\n skb_page_frag_refill+0x2bf/0x7c0 net/core/sock.c:2909\n tun_build_skb drivers/net/tun.c:1686 [inline]\n tun_get_user+0xe0a/0x66e0 drivers/net/tun.c:1826\n tun_chr_write_iter+0x3af/0x5d0 drivers/net/tun.c:2055\n call_write_iter include/linux/fs.h:2087 [inline]\n new_sync_write fs/read_write.c:497 [inline]\n vfs_write+0xb6b/0x1520 fs/read_write.c:590\n ksys_write+0x20f/0x4c0 fs/read_write.c:643\n __do_sys_write fs/read_write.c:655 [inline]\n __se_sys_write fs/read_write.c:652 [inline]\n __x64_sys_write+0x93/0xd0 fs/read_write.c:652\n do_syscall_x64 arch/x86/entry/common.c:52 [inline]\n do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83\n entry_SYSCALL_64_after_hwframe+0x63/0x6b", "severity": [ { "type": "CVSS_V3", "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L" } ], "affected": [ { "package": { "ecosystem": "Raspberry Pi OS:12", "name": "linux" }, "versions": [ "1:6.1.21-1+rpt1", "1:6.1.47-1+rpt2", "1:6.1.47-1+rpt4", "1:6.1.54-1+rpt2", "1:6.1.58-1+rpt2", "1:6.1.63-1+rpt1", "1:6.1.73-1+rpt1", "1:6.6.20-1+rpt1" ], "ecosystem_specific": { "binaries": [ { "binary_name": "linux-image-6.1.0-rpi1-rpi-v6", "binary_version": "1:6.1.21-1+rpt1" }, { "binary_name": "linux-image-6.1.0-rpi1-rpi-v7", "binary_version": "1:6.1.21-1+rpt1" }, { "binary_name": "linux-image-6.1.0-rpi1-rpi-v7l", "binary_version": "1:6.1.21-1+rpt1" }, { "binary_name": "linux-image-6.1.0-rpi1-rpi-v8", "binary_version": "1:6.1.21-1+rpt1" }, { "binary_name": "linux-image-6.1.0-rpi2-rpi-v6", "binary_version": "1:6.1.47-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi2-rpi-v7", "binary_version": "1:6.1.47-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi2-rpi-v7l", "binary_version": "1:6.1.47-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi2-rpi-v8", "binary_version": "1:6.1.47-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-2712", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v6", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v7", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v7l", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v8", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi4-rpi-2712", "binary_version": "1:6.1.54-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi4-rpi-v6", "binary_version": "1:6.1.54-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi4-rpi-v7", "binary_version": "1:6.1.54-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi4-rpi-v7l", "binary_version": "1:6.1.54-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi4-rpi-v8", "binary_version": "1:6.1.54-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi6-rpi-2712", "binary_version": "1:6.1.58-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi6-rpi-v6", "binary_version": "1:6.1.58-1+rpt2" }, { "binary_name": 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"linux-image-6.1.0-rpi8-rpi-v7l", "binary_version": "1:6.1.73-1+rpt1" }, { "binary_name": "linux-image-6.1.0-rpi8-rpi-v8", "binary_version": "1:6.1.73-1+rpt1" }, { "binary_name": "linux-image-6.6.20+rpt-rpi-2712", "binary_version": "1:6.6.20-1+rpt1" }, { "binary_name": "linux-image-6.6.20+rpt-rpi-v6", "binary_version": "1:6.6.20-1+rpt1" }, { "binary_name": "linux-image-6.6.20+rpt-rpi-v7", "binary_version": "1:6.6.20-1+rpt1" }, { "binary_name": "linux-image-6.6.20+rpt-rpi-v7l", "binary_version": "1:6.6.20-1+rpt1" }, { "binary_name": "linux-image-6.6.20+rpt-rpi-v8", "binary_version": "1:6.6.20-1+rpt1" } ] }, "database_specific": { "per_version": { "1:6.1.21-1+rpt1": { "linux_commit": "0afb5e98488aed7017b9bf321b575d0177feb7ed", "upstream_version": "6.1.21", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.1.83" }, "1:6.1.47-1+rpt2": { "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e", "upstream_version": "6.1.47", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.1.83" }, "1:6.1.47-1+rpt4": { "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e", "upstream_version": "6.1.47", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.1.83", "compiled_filter": false }, "1:6.1.54-1+rpt2": { "linux_commit": "2906f7abdc03d4a92b6b0e2e0c87ea2a9dffe8f7", "upstream_version": "6.1.54", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.1.83" }, "1:6.1.58-1+rpt2": { "linux_commit": "ccf1586ad0663fa91238ac56abf6340d6d740d18", "upstream_version": "6.1.58", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.1.83" }, "1:6.1.63-1+rpt1": { "linux_commit": null, "upstream_version": "6.1.63", "assessment": "upstream version (no usable Linux commit)", "upstream_fixed": "6.1.83" }, "1:6.1.73-1+rpt1": { "linux_commit": null, "upstream_version": "6.1.73", "assessment": "upstream version (no usable Linux commit)", "upstream_fixed": "6.1.83" }, "1:6.6.20-1+rpt1": { "linux_commit": "6f16847710cc0502450788b9f12f0a14d3429668", "upstream_version": "6.6.20", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.6.23" } } } } ], "references": [ { "type": "ADVISORY", "url": "https://www.cve.org/CVERecord?id=CVE-2024-26882" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/ec6bb01e02cbd47781dd90775b631a1dc4bd9d2b" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/77fd5294ea09b21f6772ac954a121b87323cec80" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/5c03387021cfa3336b97e0dcba38029917a8af2a" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/60044ab84836359534bd7153b92e9c1584140e4a" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/c4c857723b37c20651300b3de4ff25059848b4b0" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/f6723d8dbfdc10c784a56748f86a9a3cd410dbd5" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/ca914f1cdee8a85799942c9b0ce5015bbd6844e1" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/b0ec2abf98267f14d032102551581c833b0659d3" } ], "database_specific": { "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git", "upstream_modified": "2026-08-05T11:52:36Z", "severity": { "source": "kernel CNA", "cvss_v3_score": 7.3, "cvss_v3_severity": "High", "scenario": "AV:N - The vulnerable code runs in the GRE/gretap/ERSPAN/ipip/sit decapsulation receive path (`gre_rcv` \u2192 `__ipgre_rcv` \u2192 `ip_tunnel_rcv`), processing IP protocol 47/4/41 packets routed from anywhere on the internet. A remote attacker produces the required non-linear skb deterministically by IP-fragmenting the tunnel packet so reassembly leaves the linear area ending at the inner network header.\nAC:L - The attacker fully controls the packet layout: `pskb_may_pull()`/`__pskb_pull_tail()` pull exactly the requested bytes, so a chosen fragment split reliably leaves zero linear bytes at the inner header on every packet, and for gretap/ERSPAN the `pskb_may_pull(ETH_HLEN)` in `__iptunnel_pull_header()` lands the boundary automatically.\nPR:N - GRE and IPIP/SIT have no authentication whatsoever, and `ip_tunnel_lookup()` has wildcard-remote, collect_md and fallback-device passes that match packets from any source address, so no account or credentials on the target are required.\nUI:N - Decapsulation happens automatically in softirq context on packet receipt; no action by any local user or administrator is needed beyond the tunnel already being configured and up.\nS:U - The uninitialized read and the resulting mis-handled packet stay entirely within the kernel's own security authority; no VM, IOMMU, container or sandbox boundary is crossed.\nC:L - One to two bytes of uninitialized/stale kernel memory past `skb_tail_pointer()` (heap padding or `skb_shared_info` bytes) are read, and their low ECN bits are inferable by the attacker from whether the tunneled packet is delivered or dropped \u2014 a real but strictly bounded, low-bandwidth disclosure oracle rather than arbitrary memory read.\nI:L - No out-of-bounds write is reachable because `INET_ECN_set_ce()`/`INET_ECN_set_ect1()` bounds-check against the tail pointer, but the RFC 6040 decapsulation decision \u2014 whether the congestion (CE) signal is propagated to the inner packet and whether the frame is accepted \u2014 is driven by uninitialized memory, corrupting the ECN state of legitimate decapsulated traffic.\nA:L - The read always stays inside the skb head allocation (`skb_shared_info` follows `skb->end`), so no oops or panic is reachable on a production kernel; the effect is that legitimate tunneled packets are non-deterministically dropped via the `err > 1` path (`rx_frame_errors`/`rx_errors`), degrading the tunnel rather than the host." } } }